The use of silicones for softening fabrics, i.e., providing lubrication between fibers and yarns so they move over one another more easily, has been well known for quite some time. In addition, the use of organomodified silicones for textile treatments has also been well documented over the years (See U.S. Pat. Nos. 4,620,878, Gee, issued Nov. 4, 1986; 4,705,704, Lane et al., issued Nov. 10, 1987; 4,800,026, Coffindaffer et al., issued Jan. 24, 1989; 4,824,877, Glover et al., issued Apr. 25, 1989; and 4,824,890, Glover et al., issued Apr. 25, 1989; also of interest is Brit. Pat. Appln. 87-29,489, Walbeoff, published Dec. 18, 1987, all of said patents and said application being incorporated herein by reference). Silicones of this type are typically delivered to textiles in the form of an aqueous emulsion. More recently, much work has concentrated on the aqueous delivery of these systems via microemulsions. The above art suggests that microemulsions have two advantages over conventional "macro" emulsions: (1) they are more stable and (2) they require less mechanical energy to make.
While hand evaluation of fabrics to determine softness is still practiced widely, about 20 years ago Dr. Sueo Kawabata et al. began evaluating textiles via a mechanical approach. They designed instruments to measure low deformation forces, typical of hand analysis, on fabrics. Although these instruments (commonly known as the Kawabata Evaluation System or KES) were designed to be quality control tools for fabric acceptance, the instruments have also been used to study the effect of fabric treatments. Two such studies have been published by Union Carbide Co.: Sabia, A. J. and Pagluighi, A. M. Textile Chemist and Colorist, Vol. 19, No. 3, March 1987, p. 5; and Barndt, H. J., Sabia, A. J. and Pagluighi, A. M., Textile Chemist and Colorist, Vol. 21, No. 12, December 1989, p. 16. The shearing instrument, in particular the shearing hysteresis measurement, is believed to be indicative of the ease with which fibers and/or yarns move over one another. Thus, the lower the shear hysteresis value, the better the lubricant.
The term "reduced fiber-fiber/yarn-yarn friction" (reduced friction between individual fibers within the yarn as well as between the yarn strands) as used herein means that the fabric exhibits a lower shear hysteresis value as measured by the KES shearing instrument. While not wishing to be bound by theory, it is believed that a reduction in reduced fiber-fiber/yarn-yarn friction provides better drape, hand, and wrinkle removal during tumble drying and ironing processes due to the fibers being more easily moved over one another.